The invention relates to a brake system as well as to a load-transmitting arrangement with articulated function in particular for said brake system. The load-transmitting arrangement is used to take up and transmit a pedal force and comprises a first load-transmitting member, which has a receiving sleeve for a second load-transmitting member, wherein an end of the second load-transmitting member that projects into the receiving sleeve engages behind a snap element, which locks the second load-transmitting member against withdrawal from the receiving sleeve.
A brake system having such a load-transmitting member is known from DE 198 43 316 A1, which is incorporated by reference herein. The known load-transmitting arrangement comprises a first load-transmitting member in the form of an input member, which is a component of a master brake cylinder or of a brake booster. The input member on its end facing the brake pedal has a receiving sleeve, into which a second load-transmitting member in the form of an actuating rod projects. The end of the actuating rod that projects into the receiving sleeve is designed as a ball head. The ball head of the actuating rod interacts with a snap device, which is disposed in the receiving sleeve and takes the form of a spring sleeve having a plurality of spring elements.
In order to couple the actuating rod to the input member the actuating rod is inserted into the sleeve-shaped receiver. In said case, the ball head bends the radially inwardly projecting spring elements of the spring sleeve radially outwards. As soon as the actuating rod has been fully inserted into the sleeve-shaped receiver, the spring elements are able to snap back again. The snapped-back spring elements engage behind the ball head and hence lock the actuating rod against withdrawal from the receiving sleeve. The spring elements therefore enable a durable rapid connection between the input member and the actuating rod.
In order to realize an articulated function, the end of the input member remote from the brake pedal is designed as a joint head, which lies in a joint socket of a piston of the brake booster or of the master brake cylinder. Said articulated arrangement allows an angular deflection of the input member relative to the piston, in which the joint socket is formed. An angular deflection of the input member relative to the actuating rod, on the other hand, is prevented by the fact that the inside diameter of the receiving sleeve formed integrally with the input member is only slightly greater than the outside diameter of the actuating rod. In other words, with regard to an angular deflection the actuating rod is accommodated substantially without play inside the receiving sleeve.
For various reasons it would be desirable to allow an angular deflection of the actuating piston inside the receiving sleeve relative to the input member, while maintaining the rapid connection. Then, for example, instead of the three-part design of the load-transmitting arrangement a two-part style of construction might be selected. This would also make it possible to reduce the minimum overall length of the load-transmitting arrangement.
Since according to DE 198 43 316 A1 the end of the actuating rod that projects into the receiving sleeve is already provided with a ball head, which lies in a joint socket formed at the base of the receiving sleeve, it might be conceivable to provide play between the outside diameter of the actuating rod and the inside diameter of the receiving sleeve. The actuating rod might then be swivelled inside the receiving sleeve. The drawback of this is however that the spring elements, which engage behind and directly abut the joint head, as a result of swivelling motions of the actuating rod are continuously subject to angular deflections which after only a short time would lead to fatigue fracture of the spring tongues.
From U.S. Pat. No. 5 163 773, which is incorporated by reference herein, a further load-transmitting arrangement with articulated function is known. The known load-transmitting arrangement comprises a first load-transmitting member, which has a receiving sleeve, into which a joint head of a second load-transmitting member may be introduced. To prevent withdrawal of the second load-transmitting member from the receiving sleeve, a sleeve embracing the joint head is provided, in which the joint head is pivotally supported and which by means of a plurality of snap elements is supported in a stationary manner in the interior of the receiving sleeve.
An object of the invention is to provide an operationally reliable load-transmitting arrangement in particular for a brake system, in which a first load-transmitting member is connectable in a pivotal manner and by means of a rapid connection to a second load-transmitting member.
In a load-transmitting arrangement of the initially described type said object is achieved in that the end of the second load-transmitting member that engages behind the snap element is a joint head, which is pivotally supported inside the receiving sleeve, the second load-transmitting member being pivotally coupled to a support device, against which the snap device is supported in a non-pivotal manner. In a brake system according to the invention the first of the two load-transmitting members may form the input member for actuating a braking device, e.g. a brake-pressure generating unit or a brake booster, and the second of the two load-transmitting members may function as an actuating rod, which is to be connected to the brake pedal.
In the load-transmitting arrangement according to the invention the support device prevents a swivelling motion of the load-transmitting member disposed in the receiving sleeve from being transmitted to the snap device, which locks said load-transmitting member against withdrawal. The snap device is consequently uncoupled by means of the support device from swivelling motions of the load-transmitting member disposed in the receiving sleeve. Said uncoupling therefore prevents swivelling motions between the two load-transmitting members from causing fatigue fractures in the snap device.
The support device is preferably connected in a pivotal but axially immovable manner to the load-transmitting member disposed in the receiving sleeve. After said load-transmitting member has been introduced into the receiving sleeve, the support device as well as the joint head may engage behind the snap element. The snap element may then be supported by means of the support device e.g. against the receiving sleeve or against the load-transmitting member on which the receiving sleeve is formed. Inside the receiving sleeve the support device may abut a stop or a slope and be biased by a resiliently designed snap element towards the receiving sleeve or the load-transmitting member on which the receiving sleeve is formed. In said case, after establishment of the rapid connection between the two load-transmitting members the support device is fixed in axial direction inside the receiving sleeve and connected in a non-pivotal and non-rotatable manner to the support device.
The support device may be designed in various ways. For example, according to a first embodiment it is possible to provide an annular support device, which is supported rotatably and pivotally on the load-transmitting member to be introduced into the receiving sleeve and may be situated in abutment with the joint head. The annular support device at its side facing the joint head preferably comprises a bearing surface for the joint head. After the load-transmitting member has been introduced into the receiving sleeve, the annular support device may abut a step inside the receiving sleeve. According to a second, preferred embodiment the support device embraces the joint head at least in sections and is pivotable relative to the latter. In said case too, the support device in the style of a joint socket may additionally function as a bearing for the joint head. A joint socket for supporting the joint head may also be constructed integrally with the receiving sleeve or the load-transmitting member on which the receiving sleeve is formed. Thus, the base of the receiving sleeve may have the shape of a joint socket.
When the joint is realized by means of a joint head and a complementary joint socket, the joint head is advantageously a ball head, which is supported in a calotte-shaped joint socket. Instead of a joint socket other bearings may be used, such as e.g. bolts, which extend through corresponding openings of the joint head and the receiving sleeve. In accordance with the aspect of a rapid connection, support in a joint socket is however preferred.
The support device may be of a one- or multi-part design. It may, for example, comprise two half-shells, which embrace the joint head. Preferably a support device embracing the joint head is designed in such a way that in every operating state of the load-transmitting arrangement the joint head has a specific amount of play inside the support device. The joint head is then freely pivotable inside the support device.
The individual parts such as e.g. half-shells of the support device may be connected to one another by means of one or more flexible webs. Such a construction of the support device guarantees an easy assembly.
The bottom of the receiving sleeve may have an inside diameter tapering in the direction of actuation of the pedal. Preferably, given such a construction of the receiving sleeve, the support device has a complementary outside diameter tapering in the direction of actuation of the pedal. Such a construction of the receiving sleeve and the support device guarantees self-centring of the support device when the latter, together with the load-transmitting member carrying the joint head, is introduced into the receiving sleeve. Furthermore, by means of such a shaping of receiving sleeve and support device it may be guaranteed, in the case of a multi-part support device, that the individual parts of the support device are automatically fixed relative to one another. In addition, for fixing a multi-part support device which embraces the joint head, one or more retaining rings may be provided, which e.g. prevent the support device from detaching from the joint head.
The snap element may be realized in various ways. According to a preferred embodiment a snap device in the form of a spring sleeve is provided, which as a snap element has at least one spring element. The spring sleeve may comprise one, two or more spring elements, which interact with the support device and which radially surround the outside of the load-transmitting member disposed in the receiving sleeve. In an advantageous manner the individual spring elements are separated from one another by slots extending substantially in axial direction.
According to a particularly preferred embodiment of the invention each spring element via a free end, which is actuable resiliently in a radially outward direction, interacts with an oblique surface formed on the support device. Said oblique surface may have a radial extension that increases in the direction of actuation of the pedal. The oblique surface of the support device is preferably arranged inclined in such a way relative to each spring element that the free end of the spring element runs approximately vertically into the oblique surface. Given such an arrangement, the introduction of load from the oblique surface into the spring element and vice versa is optimal, i.e. the spring element with a maximum force opposes the support device and/or the load-transmitting member coupled to the support device.
The e.g. conically designed oblique face has the further advantage that, depending on the actual position and size of the components involved in the rapid connection, the snap elements may act at a lower and higher point upon the slope. In every possible tolerance situation, therefore, a play-free connection between the spring elements and the detent device is guaranteed.
The spring sleeve may have an axial slot extending over the entire length of the spring sleeve as well as a detent collar extending radially outwards. The axial slot allows a flexible reduction of the diameter of the detent collar so that the latter may interact with a groove formed radially at the inside of the receiving sleeve in order to fasten the spring sleeve inside the receiving sleeve.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.